This invention relates generally to pulse tube refrigeration systems.
A recent significant advancement in the field of generating refrigeration is the pulse tube system wherein pulse energy is converted to refrigeration using an oscillating gas. In such pulse tube systems a pulse is provided to a working gas which is then cooled in a regenerator. The cooled oscillating gas is expanded in the cold end of a pulse tube and the resulting refrigeration is used to cool, liquefy, subcool and/or densify a product fluid. The oscillating gas then cools the regenerator for the next pulse cycle.
The application of pulse tube technology has primarily been for small quantities of refrigeration typically at very low temperatures. There are a number of very attractive features of pulse tube refrigeration systems that are already in service for small refrigeration requirements. Among such attractive features are no cold moving parts, low maintenance and corresponding high reliability, ease of fabrication, no vibration and low cost. Most of these features are also strong incentives for scale up to industrial size. However one deterrent to large scale application of pulse tube refrigeration is the relatively high power requirement needed to generate the refrigeration.
Accordingly, it is an object of this invention to provide a pulse tube refrigeration apparatus which can be used to generate refrigeration with less power on a unit refrigeration basis than can heretofore available pulse tube systems.
The above and other objects, which will become apparent to those skilled in the art upon a reading of this disclosure, are attained by the present invention which is:
A pulse tube refrigeration apparatus comprising:
(A) a pulse generator;
(B) a work transfer tube having a receiving end for receiving a pulse from the pulse generator, and a dispensing end in flow communication with a regenerator, said receiving end having a cross sectional area which differs from the cross sectional area of the dispensing end;
(C) a pulse tube in flow communication with the regenerator; and
(D) a cold heat exchanger disposed between the regenerator and the pulse tube.
As used herein the terms xe2x80x9cpulsexe2x80x9d and xe2x80x9cpressure wavexe2x80x9d mean energy which causes a mass of gas to go through sequentially high and low pressure levels in a cyclic manner.
As used herein the term xe2x80x9corificexe2x80x9d means a gas flow restricting device placed between the warm end of a pulse tube and a reservoir.
As used herein the term xe2x80x9cregeneratorxe2x80x9d means a thermal device in the form of porous distributed mass, such as spheres, stacked screens, perforated metal sheets and the like, with good thermal capacity to cool incoming warm gas and warm returning cold gas via direct heat transfer with the porous distributed mass.
As used herein the term xe2x80x9cindirect heat exchangexe2x80x9d means the bringing of fluids into heat exchange relation without any physical contact or intermixing of the fluids with each other.
As used herein the term xe2x80x9cdirect heat exchangexe2x80x9d means the transfer of refrigeration through contact of cooling and heating entities.
As used herein the term xe2x80x9cwork transfer tubexe2x80x9d means a tube wherein a pulse or pressure wave is transferred in an adiabatic manner.